1. Field of the Invention
This invention relates, in general, to hydraulic couplings, and specifically to hydraulic couplings used in undersea drilling and production applications. More particularly, the invention involves a hydraulic coupling with at least two flexible, pressure-energized seals positioned in the annular space between the male and female members.
2. Description of the Related Art
Subsea hydraulic couplings are old in art. The couplings generally consist of a male and a female member with sealed fluid passageways connecting therebetween. The female member generally is a cylindrical body with a relatively large diameter longitudinal bore at one end and a relatively small diameter longitudinal bore at the other. The small bore facilitates connections to hydraulic lines, while the large bore seals and slidingly engages the male member of the coupling. The male member or probe includes a cylindrical portion at one end having an outer diameter approximately equal to the diameter of the large bore of the female member of the coupling. The male member also includes a connection at its outer end to facilitate connection to hydraulic lines. When the cylindrical portion of the male member is inserted into the large bore of the female member, according to various embodiments of the device, fluid flow is established between the male and female members.
In U.S. Pat. No. 4,694,859 to Robert E. Smith III, an undersea hydraulic coupling and metal seal is disclosed. This patent provides a reusable metal seal which engages the circumference of the probe and is positioned in the annulus between the male and female members. The metal seal is pressure-energized to expand radially inwardly and outwardly during use. The metal seal is held in place by a retainer.
Problems arise with use of hydraulic couplings in relatively high pressure systems due to the high axial forces imposed on the male and female members during the coupling operation and during their use. In such couplings, it is necessary for the fluid force opposing the face of the male or female member to be overcome before the fluid communication is established between the members. In a relatively high pressure system, high forces imposed on the valve members may render the connection of the male member to the female member very difficult. Also, during use, fluid pressure is exerted between the male and female members in such a way as to tend to separate them. The force necessary to join the members and the resultant tendency of the body members to separate are characteristic problems in the prior art. High pressure systems and undersea applications also experience problems associated with sealing the junction between the male and female members.
Ideally, hydraulic couplings should, as far as possible, be pressure balances so that fluid pressure does not hinder connection or urge separation of the male and female members. Preferably, to prevent loss of fluid in coupling or uncoupling, the members should include valve means to open automatically on coupling and close automatically on uncoupling. Finally, the coupling should employ seals which can withstand high pressures as well as the corrosive effects of adverse environments. The present invention solves all of these needs and requirements.
A pressure balances undersea hydraulic coupling is shown in U.S. Pat. No. 4,754,780 to Robert E. Smith III. In the '780 patent, hydraulic couplings are disclosed wherein fluid communication between the male and female coupling members is through radial fluid passages in the members.
In U.S. Pat. No. 4,832,080, a pressure balanced hydraulic coupling with metal seals is disclosed. In the '080 patent, a pair of metal seals are positioned to seal between the circumference of the male member and the central bore of the female member, and a seal retaining member having a radial passage is positioned in the annulus therebetween, such that the seals are on each side of the radial fluid passage. The seals in the '080 patent are pressure energized metal seals of the type shown in U.S. Pat. No. 4,694,859 to Robert E. Smith III. U.S. Pat. No. 4,754,780, 4,832,080 and 4,694,859 are incorporated herein by reference.